Field of the Invention
The present invention relates to a servomotor controller having a function of compensating the position of a driven body that is driven by the power of a servomotor, a servomotor control method, and a computer-readable recording medium.
Related Art
Conventionally, servomotor controllers have been known which install a workpiece (work) on a table, and cause the table to move via a connection mechanism by a servomotor. The table and workpiece are driven bodies. The connection mechanism has a coupling which is connected to the motor servo, and a ball screw which is fixed to the coupling. The ball screw is threaded to a nut. In one of such servomotor controllers, there is a servomotor controller having a function of compensating the position of a driven body (referred to as mobile body) that is driven by the power of the servomotor.
A servomotor controller disclosed in Patent Document 1 estimates a drive force acting on a driven body at a connecting unit of the connection mechanism, and compensates a position command value based on the estimated drive force. A servomotor controller disclosed in Patent Document 2 calculates a stretch/contraction amount of the ball screw from a distance from the servomotor to the mobile body, and a torque command value, and calculates a position compensation amount for the mobile body threaded to the ball screw from this stretch/contraction amount, and compensates the position command value according to this position compensation amount. A servomotor controller disclosed in Patent Document 3 calculates an stretch/contraction amount of a ball screw based on a tension acting on a distal side of the ball screw from the servomotor, a distance between a pair of fixing units supporting the ball screw at both ends, a distance from the fixing unit provided at a proximal side of the servomotor to a movable body, and a torque command given to the servomotor, and calculates a position compensation amount for a feed shaft based on the calculated stretch/contraction amount of the ball screw.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2014-109785
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2014-13554
Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2014-87880